Rheostat with magnetic operator



April 19, 1949. P. s. RAMOS 2,467,497

RHEosTAT WITH MAGNETIC OPERATOR Filed lay 17, 1946 Patented Apr. 19, 1949 RHEOSTAT WITH MAGNETIC OPERATOR Pedro S. Ramos, Chicago, lll., asslgnor to Electra Voice Corporation, Chicago, Ill., a corporation of Delaware Application May 17, 1946, Serial No. '670,319

(ci. 201-56) v ll Claims.

The present invention relates in general to sealed electrical apparatus, and has more particular reference to current ilow equipment, including adjustable devices such as switches, resistance units, and the like.

An important object of the present invention is to provide an electrical current flow controlling device, including adjustably movable elements enclosed in a sealed envelope, with connecting means extending outwardly of the envelope for connecting the adjustable elements in external electrical circuits, devices embodying the present invention having associated means disposedoutwardly of, and preferably mounted on, the envelope, and operable, outwardly of the envelope, to eliect adjusting movement of the envelope enclosed elements of the device.

Another important object is to provide devices, including envelope enclosed elements adapted for relative adjustment within the envelope, in combination with adjusting means mechanically disconnected irom said adjustable elements and disposed entirely outside of the envelope, yet operable, outwardly of the envelope, to induce adjusting movement of the adjustable elements; a further object being to induce such adjusting movement of the elements by electromagnetic action, accomplished through the walls of the enclosing envelope means.

Another important object is to provide a ilow control unit comprising relatively adjustable elements sealed within an enclosing envelope of nonmagnetic material, such as glass, and to provide for the relative adjusting movement of said elements from outwardly of the envelope by mounting magnetic means on at least one of the elements, whereby said element may be moved with- Y in the envelope in response to the movement of cooperating magnetic means .disposed entirely outside of the envelope.

Another important object is to provide an electrical resistance unit, such as a rheostat or potentiometer, enclosed in an envelope of nonmagnetic material, and including a movable resistance adjusting element within the envelope and carrying magnetic means on such movable element, in combination with movable means mounted outwardly of the envelope and carrying magnetic means in position to move in a path registering with the path of movement of the magnetic means within the envelope, whereby adjusting movement of the magnetic means, outwardly of the envelope, may result in the adjustment of the movable element within the envelope.

Another important object is to provide sealed means of the character mentioned that will perform its circuit controlling function regardless of surrounding moisture, the electrical characteristics of devices embodying the present invention remaining constant throughout the service life of the device, regardless of surrounding atmospheric conditions. As a consequence, Vadjustable resistance units and other devices embodying the present invention may be successfully used in radio, electronic, and other electrical apparatus, under conditions which seriously impair the operating characteristics of circuit control devices of the sort heretofore provided, the operating elements of which are exposed to the surrounding atmosphere.

The foregoing and numerous other important objects, advantages, and inherent functions of the invention will become apparent as the same is more fully understood from the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodiment of the invention.

Referring to the drawings:

Fig. 1 is a sectional viewthrough a resistance unit embodying the present invention;

Fig, 2 is a sectional view taken substantially along the line 2--2 in Fig, 1;

Fig. 3 is a perspective view of a mounting bracket forming a part of the unit shown in Fig, 1; and

Fig. 4 is a sectional view taken substantially along the line i-- in Fig. 1.

To illustrate the invention, the drawings show an electrical circuit controlling device, comprising a pair of relatively movable elements il and I2 sealed within an envelope i3, and means ll mounted and disposed outwardly of the envelope and operable to accomplish relative movement of the elements ll and l2.

To this end, the envelope i3 comprises nonmagnetic material, such as glass, although other non-magnetic material may, of course, be employed. To accomplish relative movement of the elements ll and l2 within the envelope, one of said elements, such as the element ll, may be anchored against movement in the envelope, while the other element, as the element l2, may be movably supported within the envelope. Magnetic means, such as a permanent magnet l5, may be mounted in any suitable or preferred fashion on the member I2, and supported in position thereon to move with the element l2 in a.

path immediately within a wall l5 of the envelope. The adjusting means Il vmay comprise a such as a permanent magnet I8, for movement in a path corresponding with the path of movement of the magnet I5, the magnets I5 and I8 beingdisposed with facing ends on opposite sides of the envelope wall portion I6. When the member I'I is moved outwardly of the envelope, a corresponding movement of the arm I2 will be accomplished within the envelope, by virtue of the magnetic connection through the envelope wall I6 between the magnets I5 and I8.

As a consequence of the foregoing arrangement, the elements II and I2 may be relatively adjusted from outwardly of the envelope, while remaining at all times, during the service life of the unit, entirely sealed and protected from the surrounding atmosphere. The envelope i3 preferably comprises an hermetic seal around the enclosed elements II and I2. If desired, the envelope may be evacuated, or may be filled with a suitable inert gas, for the protection of the enclosed elements. In any event, the sealed elements are adapted to maintain predetermined electrical characteristics thereof substantially unchanged throughout the service life of the unit.

As shown, the envelope I3 preferably comprises a cup-shaped base I9 and a cover member 20, forming the envelope wall I6. The cover 20 may be provided with annularly flanged marginal portions 2|, sized to t within the open end of the cup-shaped base I9 and sealed in place. The base and cover may conveniently be made of glass, and may be sealed together by usual glass sealing methods after the elements II and I2 have been assembled therein.

The elements II and I2 may be supported lwithin the envelope I3 in any convenient or preferred fashion. As shown, the members are mounted on a support pedestal 22. This pedestal preferably is mounted centrally within the envelope, and comprises a base portion 23 sealed in and supported by the bottom wall of the cupshaped base I9. To this end, the base portion 23 may comprise a metal adapted to seal with the glass material of the base I9. A conductor wire 24 of metal, also preferably sealable to glass, is electrically connected to the base portion 23 and extends thence outwardly of the envelope through a glass-to-metal seal 25 in the base I9. The base portion 23 may include a projecting stem, 'comprising `a` spindle portion 26 and a threaded portion or stud 21. The element I2 preferably comprises a resilient strip forming an i arm at one end for. rotational engagement on the spindle portion 26,.whereby said arm may extend radially outwardly of the pedestal 22 and rotate about theaxis .of said pedestal.,` The element I2 is securedion. the spindle portion 26 by a pedestal extension.. 28, having` anl :internally threaded lsocket for -receiving v.the threaded spindlefportion. 2T. Iff desired, a .spring washer" shown, themagnet `I8`maycomp1vise` a horseshoe y magnet mounted bylugs on thebracket I'Lcom- .6.07.

29 mayfbe held on.the spindle portion v26 with th'epivoted end *of the. arm I2', by the pedestal extension 28' loperating as a holding nut, when- 'I ends in position to supportingly engage the element Il in order to support said ends on the pedestal 22.

The element III, in the illustrated embodiment. comprises a resistance unit o! any preferred character, as, for example, a curved strip 3l of insulating material secured at its opposite ends on the arms 33, and having a resistance conductor 35 mounted on the strip in helically Wound coils. The resistance conductor, however, may take any preferred form and may be mounted on, or in, the support strip as in any suitable manner; for example, the strip 236 may itself comprise resistance material, in which case suitable insulation should be provided between the opposite ends of the strip 34 and the mounting pedestal 22, to prevent the electrical connection of the resistance element with the pedestal through the bracket 3i'. The opposite ends of the resistance means 35, whether a resistance wire wound on the strip Bil, or whether the same comprises resistance material incorporated in the strip 3d, are electrically connected, as by connecting elements 36, with conductors 3l extending outwardly of the envelope, as through glass-to-metal seals 38 formed in the walls of the envelope.

When mounted in the envelope, the end of the element I2 remote from the pedestal 22 makes yielding contact with the resistance means 35, as at and along an edge of the curved strip 35, the resilience of the arms I2 serving to press its pedestal remote end upon the element II. The magnet I5 may comprise a small horseshoe magnet anchored by support lugs 39 on the arm I2 immediately within theresistance element li. the bracket 39 serving to support the magnet immediately within the envelope wall i6, whereby the arm I2 may be turned about the axis of the pedestal 22, from one end of the resistance element Il to the other end thereof, by magnetic action exerted upon the magnet I5 through the overlying envelope wall IS.

After the elements I I and I2 have been mounted in the base I9, as aforesaid, the cover 20 may be applied Within the open end of the cup-shaped base, the flanged portions -2l of the cover snugly encircling the resistance element II and aiding in supporting the same in position within the envelope. After the cover has been so assembled, it may be sealed to the cup-shaped base in any preferred fashion, whereby the enclosed elements I I and I2 are hermeticallyenclosed and isolated from the surrounding atmosphere.

Any suitable` arrangementmay be employed for mounting the actuating'magnet I8in position to move the'magnet I5 within thelenvelope, As

prising an arm.` mounted ,for rotatiomxoutwardly of theenvelope,v about thef'axisof the pedestalv f ZZV-whereby the magnetijisfguidedto move in a track across theenvelopewall I-S, immediately Aoutwardlythereof and registering' with the pathl `of movement ofthe magn'etfglwithin the env velope.

may comprise a bracket having; arms IIJ` -for- 'I o .this end, theasu'pporting:means-L14 mounting the same on` the envelopev I3, said arms havingterminal lugs vr4I adapted ,to engage Y' in seats 4 2 formed-inthe outer/surfacesofthe en- Y. velope, as onthe bottom ofthe base I9.` The j armsk 4U, inwardly ofthe flugs, 'areadapted toiseat in grooves 43 formed inv the side: walls of ythe base; and the arms maybe formed, with inwardlyrstruck'lugs','in position to engage the envelope.l as at the edges of the cover means 20, whereby the bracket is held .on the envelope by and between the lugs 4I and 44. The bracket may, also, include a central portion 45 formed with an opening 46, in which is mounted a support bushing 41 carrying a turnable spindle 48, the magnet carrying arm I1 being attached, as at one end of the spindle 48. A suitable operating handle or knob may be secured to the spindle 48, at the end thereof remote from the arm I1, in order to facilitate the turning of the spindle in order, thus, to movel the arm I1.

It is thought that the invention and its numerous attendant advantages will `be fully understood from the foregoing description, and it is obvious that numerous changes may be made in the form, construction and arrangement of the several parts without departing from the spirit or scope of the invention, or sacrificing any of its attendant advantages, the form herein disclosed being a preferred embodiment for the purpose of illustrating the invention.

The invention is hereby claimed as follows:

l. An adjustable electrical unit comprising .sealed envelope means, a pair of elements magnetic material, and outer magnetic means mounted outwardly of said envelope and movable adjacent said wall portion, whereby to adjustably shift said movable element by magneticaction exerted through said envelope wall portion between said inner and outer magnetic means.

2. An adjustable electrical unit comprising an envelope, a pair of elements mounted within the envelope. one of said elements comprising an arm supported for relative swinging movement with respect to the other element and having a portion adapted to electrically engage said other element, inner magnetic means connected with said arm and supported thereby in position to move adjacent, and movable in a path extending across, a fiat wall portion of said envelope, said wall portion comprising non-magnetic material, and outer magnetic means mounted outwardly of said envelope and movable adjacent said wall portion, in a path registering with the path of said inner magnetic means, whereby to adjustably shift said movable element by magnetic action exerted through said envelope wall portion between said inner and outer'magnetic means.

3. An adjustable electrical unit comprising an envelope, a pair of elements mounted within the envelope. one of said elements comprising4 an arm, pivotally supported for relative swinging movement with respect to the other element, about a pivot axis, and having a portion adapted to electrically engage said other element, inner magnetic means connected with said arm and supported thereby in position to move in an arcuate path adjacent a wall portion of said envelope, said wall portion comprising non-magnetic material, and outer magnetic means mounted outwardly of said envelope and movable in an arcuate path adjacent said wall portion, and in regis tration with the arcuate path of said inner magnetic means, whereby to adjustably shift said lmovable element by magnetic action exerted 'lol through said envelope wall portion between said inner and outer magnetic means.

4. An adjustable electrical unit comprising an envelope, a pair of elements mounted within the envelope, one of said elements comprising a movable member adapted to shift with respect to the other element, magnetic means connected with one of said elements and supported in position to move adjacent a wall portion of said envelope, said wall portion comprising glass, magnetic means and means to pivotally mount the same for movement, outwardly of said envelope, in an arcuate path adjacent said wall portion, whereby to adjustably shift said movable element by magnetic action exerted through said envelope wall portion between said inner and outer magnetic means.

5. An adjustable electrical unit comprising an envelope of glass, a pair of elements mounted within the envelope, one of said elements comprising a movable member adapted to shift with respect to the other element, inner magnetic means connected with one of said elements and supported in position to move adjacent a flat non-magnetic wall portion of said envelope, outer magnetic means and means to mount the same for turning movement about a pivot axis, outwardly of said envelope, in position to move across said flat wall portion, in spaced registration with said inner magnetic means, whereby to adjustably shift said movable element by magnetic action exerted through said envelope wall portion between said inner and outer magnetic means.

6. An adjustable electrical unit comprising an envelope, a pair of elements mounted within the envelope, one of said elements comprising an arm supported for pivotal movement with respect to said other element, inner magnetic means mounted on said arm in position to move in an arcuate path of movement adjacent a wall portion of said envelope, said wall portion comprising non-magnetic material, and outer magnetic means mounted outwardly of said envelope and movable in an arcuate path registering with the arcuate path of movement of the other inner magnetic means adjacent said wall portion, whereby to adjustably shift said movable element by magnetic action exerted through said envelope wall portion between said inner and outer` magnetic means.

7. An adjustable electrical unit comprising an envelope, a pair of elements mounted within the envelope, one of said elements'comprising an arcuate resistor, and the other element comprising an adjustable resistor contacting arm mounted for swinging movement on a pivot axis, inner magnetic means connected to said contacting arm in position to move adjacent a Wall portion of said envelope in an arcuate path centered on said axis, said wall portion comprising non-magnetic material, and outer magnetic means pivotally mounted outwardly of said envelope and movable adjacent said Wall portion in an arcuate path registering with the path of movement of said inner magnetic means, whereby to adjustably shift said contacting member by magnetic action exerted through said envelope wall portion between said inner and outer magnetic means.

8. An adjustable electrical unit comprising an envelope, a central support providing a pivot axis in said envelope, a pair of relatively adjustable elements mounted Within the envelope, one of said elements comprising an elongated member, disposed circularly about said central support.

and the other element comprising an,` arm pivv oted on said support in position to move along the elongated member, inner magnetic means connected with said arm in position to move therewith adjacent a wall portion of said en velope, said Wall portion comprising non-magnetic material, and outer magnetic means mounted outwardly of said envelope for movement adjacent said wall portion in a circular path about said pivot axis, whereby to adjustably shift said movable element on said support by magnetic action exerted through said envelope wall portion between said inner and outer magnetic means.

9. An adjustable electrical unit comprising an envelope having a cylindrical wall and a at end wall, a pair of relatively adjustable elements mounted within the envelope, one of said elements comprising an arcuate member supported within and by a portion of said cylindrical wall,

jacent said end wall, whereby to adjustably shift said movable element by magnetic action exerted through said end wall between said inner and outer magnetic means. Y

10. An adjustable electrical unit comprising an envelope formed in sections, one section comprising an open ended cylindrical casing and another section forming a at end closure for the casing, a pair of elements mountedon one of said sections and enclosed within the envelopeV by the other section, one of said elements comprising an arm pivoted for turning movement Within the cylindrical casing about the central axis thereof, inner magnetic means connected with said arm in position to move within and adja- `non-magnetic material,

cent said end closure, said closure comprising and outer magnetic means mounted outwardly of said envelope and movable adjacent said end closure, whereby to adjustably shift said arm by magnetic action exerted through said cover closure between said inner and outer magnetic means.

11. An adjustable electrical unit comprising an envelope formed in sections, one section comprising an open ended casing having a cylindrical side wall and another section comprising nonmagnetic material forming a fiat end closure for the casing, a central support mounted in said envelope and providing a pivot axis substantially in alinernent with the axis of said cylindrical casing, a pair of elements mounted in said envelope, one of said elements comprising an arcuate resistor supported within the cylindrical wall of said casing, the other of said elements comprising an arm pivoted on said support and having a support remote portion adapted' to electrically engage and ride upon said resistor, an inner magnet secured on said arm in position to move therewith adjacent and within said end closure, in an arcuate path centered on said pivot axis, an outer magnet, and means to support the same on said envelope and outwardly of ably shifted along said lresistor by magnetic action exerted through said end closure between said inner and'outer magnets.

'PEDRO s. RAMos.

REFERENCES CITED The following references are of I record in the file of this patent:

UNITED STATES PATENTS Number Name v -Date Y 2,256,833 MCDOna1d- Sept. 23, 1941 

